C# DLL run-time error - builds, runs, but throws unhandled exception upon trying to use DLL functions

Question

I am trying to compile the example project shown here for C#. It had to be converted to VS2010, but that worked fine. It builds, runs, but then dies when it tries to access a DLL function.

I made a series of images to show my steps. As you can see, the device I designed is attached and correctly configured, but I really don't think that has anything to do with the issue. Inside the Form1.cs file, the following comment explains how to use the DLL:

/*
PLEASE NOTE
You must add a reference to the FTChipIDNet.dll in order to use this sample
To do this:
1. Click on Solution explorer tab.
2. Right click the References tree.
3. Choose Add Reference option.
4. Browse to the FTChipIDNet.dll (as a personal preference I place this in my bin directory)
5. Click OK
*/

I followed the instructions shown above and the undefined reference to the namespace FTChipID was fixed. I also manually checked the Object Browser to be sure the GetNumDevices function exists and it does.

Clicking the button produces this error:

DLLNotFoundException was unhandled:

Unable to load DLL 'FTChipID.dll': The specified module could not be found. (Exception from HRESULT: 0x8007007E)

at this line of code:

FTChipID.ChipID.GetNumDevices(ref numDevices);

Now, you may be thinking "the error says it needs FTChipID.dll, not FTChipIDNet.dll." I'm wondering the same thing. I have FTChipID.dll along with a .lib and .h file, but I don't know how to use them or where they need to be in order for this program to find them. I tried adding a reference to FTChipID.dll, but VS2010 said

A reference to ...\FTChipID.dll could not be added. Please make sure that the file is accessible, and that it is a valid assembly or COM component.

I don't know what that means either. Any ideas? Thanks in advance.

Answer 1

FTChipIDNet.dll is a wrapper for the FTChipID.dll, so you need to add the reference to your solution (as you did above) and then copy the FTChipID.dll to the bin folder there FTChipIDNet.dll will be located.

Both dll's should be located in your solution's bin folder to operate and should not be located in windows\system32.

Answer 2

I built the FTDI sample program "CSChipID" in VS2013 using a build to "Any CPU". The two DLL files "FTChipID.dll" and "FTChipIDNet.dll" were copied to the bin directory, but I continued to get errors when the first DLL function was called, "FTChipID.ChipID.GetNumDevices(ref numDevices);" The fix is change the build to "x86" as follows.

Build - Configuration Manager Active Solution Platform - "x86" Note: If "x86" is not available, select -New...- to select "x86".